Human serum albumin, or HSA, is a crucial blood protein which is used in the treatment of severe burns, liver cirrhosis, and hemorrhagic shock, is used in vaccine production, and has one rather sticky requirement — it has to be extracted from clean, donor blood.

While that's not a lot of the stuff, it's physically and chemically equivalent to blood-derived HSA, and worked just as well in rat treatment. And while finding blood donors can be hard to do at the best of times, humans are already pretty good at growing rice, and the possibility of further modifying the seeds could make it even more effective.